PB2309: EVALUATION OF MORBIMORTALITY FACTORS OF PATIENTS WITH ACQUIRED THROMBOTIC THROMBOCYTOPENIC PURPURA
Authors: M. I. Pinto, B. Marques, D. Coelho, P. Martinho, T. Fidalgo, J. P. Carda, A. B. Sarmento Ribeiro
Journal: HemaSphere (2022)

Background: Acquired Thrombotic Thrombocytopenic Purpura (aPTT) is a rare disease caused by the action of antibodies against ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13), with high mortality when not treated properly. Formerly, it was defined by the pentad of fever, microangiopathic hemolytic anemia, thrombocytopenia, neurological symptoms and severe acute kidney injury. Currently, it is characterized by the presence of microangiopathic hemolytic anemia, thrombocytopenia and variable target organ lesion. Despite its rarity, a prompt diagnosis is essential and the overlapping symptoms with other thrombotic microangiopathies, as well as the multiplicity of nonspecific manifestations, makes its diagnosis highly challenging. Aims: To study in detail the natural history of aPTT and possible morbimortality factors associated on the moment of diagnosis and its evolution on the first 30 days of disease. Methods: Retrospective evaluation of patients diagnosed with aPTT between 2009 and 2019 in a terciary center. Results: There were 26 patients included in this study, with a median age of 41 years and of which 58% (n=15) were female. At the time of diagnosis, 16 patients (62%) presented neurological manifestations, but only 2 (11%) of the patients submitted to CE-CT had imagiological findings. Cardiac involvement, defined by troponin’s elevation, was observed on 14 patients of the 16 whom have measured it (54%). Other manifestations of the disease included haemorrhage, mainly petechiae and ecchymosis (n=11; 42%), fever (n =10; 39%) and renal dysfunction (n =7, 27%). Only 1 patient presented with the classic pentad. On blood analysis, 73% of the patients presented with haemoglobin levels below 9 g/dL (median: 8,2g/dL) and 77% with a platelet count below 30x109 (median: 15x109/L).Five patients (19,5%) had a previous diagnose of a comorbid autoimmune disease. Most patients were treated with plasmapheresis (85%, n=22) and/or corticotherapy (89%, n=23). From the patients treated with plasmapheresis, 19 (73%) started the treatment on the day of admission or first day of hospitalization. The mortality in this sample was 27% (n=7): 3 patients (12%) died due to acute aPTT and the remaining 4 from other causes (3 from an oncological disease and 1 from septic shock). Progression free survival (PFS) and Global survival (GS) were 77% and 81% on the first year, and 60% and 73% at five years, respectively. Patients treated with plasmapheresis only on the beginning of the 2nd day after admission showed significant worse GS compared to those who started the same treatment sooner (HR =8,44, p=0.022, IC 1,35 = [1,35-52,65]. Older age (M=61,67, DP=19,21) was associated with marginally significance to therapeutic refractoriness (p=0.089). The presence of neurological symptoms, fever, high troponin levels, low hemoglobin, a raise of LDH and low platelet counts did not interfere significantly on the PFS and GS. Summary/Conclusion: aPTT is a rare and severe disease that should be promptly diagnosed, since time until the beginning of treatment is determinant on the disease mortality. Given the wide range of differential diagnosis and the variability of symptoms, the presence of microangiopathic hemolytic anemia associated with thrombocytopenia should raise our clinical suspicion. Although organ dysfunction has been proved to have an impact on prognosis, this association was not demonstrated in our sample, probably due to the early initiation of treatment.